Anti-magnetic watch



(No Model.)

C. 'I'. MASON. ANTI MAGNETIC WATCH. No. 406,364. Patented July 2, 1889.

ATTORNEYS.

UNITED STATES PATENT OEEICE.

CHARLES T. MASON, OF SUMTER, SOUTH CAROLINA, ASSIGNOR, RY DIRECT AND MESNE ASSIGNMENTS, TO THE AMERICAN IVALTHAM TATCH COM' PANY, OF MASSACHUSETTS.

ANTI-MAGNETIC WATCH.

SPECIFICATION forming part of Letters Patent No. 406,364, dated July 2, 1889.

Application filed June 26, 1888. Serial No. 278,256. (No model.)

To all whom it may concern:

Be it known that. I, CHARLES T. MAsoN, of Sumter, inthe county of Sumter and State of South Carolina, have invented a new and Im- 5 proved Magnetic Shield for Vatch-Balances,

of which the following is a specilicatiomreference being had to the annexed drawings, forming a part thereof, in Which- Figure l is a plan view of a Watch-moverc ment to which my improvement has been applied, and Figf is a transverse section taken on line oc in Fig. l.

Similar letters of reference indicate corresponding parts in both views. i5 The obj ect of my invention is to provide a simple and eiective device Jfor protecting the balances of Watches from magnetism.

My invention consists in an annular cese surrounding` the balancewvheel a short diseo tance from its periphery and permanently secured to the lower Watch-plate. The Watch-movement A is of the usual description, having the balance B formed of brass and steel and provided with the. hair-- 2 5 spring ct. Around the peripheryT of the balance-Wheel is placed a ring C, of soft iron, provided with an inwardly-projecting flange or fillet b, which isl secured to the bottom plate of the Watch by screws c, as shown in Fig. l.

' 3o It is Well known that a magnetic body surrounded or inclosed by a body of soft iron is shielded from external magnetic iniiuences. I have made use of this principle in my improved shield for Watch-balances by surrounding the balance with sott iron, thereby pre- 35 venting the steel of the watch-balance from being magnetizcd by induction from the eX- ternal magnets.

My improved device can be applied to and form a part of a new Watch, 6r it may be read- 4o ily adapted to Watches already in use.

It the mainspring or other steel part ot a Watch provided with my improved shield be magnetized, it will have no effect upon the operation of the Watch, as the magnetism, 45 which would Without the shield act upon the balance, will be absorbed by the ring C.

Having thus described my invention, I claim as ner and desire to secure by Letters Patentl. The combination, With a Watch-balance, 5c of a ring of magnetic metal encircling or surrounding the said Watch-balance, substantially as described.

2. The combination, with the balance-Wheel of a Watch,of asott-iron ring surroundingthe 55 balance-Wheel, substantially as specified.

3. The combination, with a balance-Wheel of a Watch, of a ring of soft iron surrounding the balance-Wheel and provided with an inwardly-proj ecting liange on its lower part, sub- 6o stantially as herein shown and described.

CHARLES T. MASON.

Vitncsses:

C. C. HOYT, WM. N. RAFEIELD. 

